Tricky SQL - is it possible using just SQL and no PL/SQL

Question

Hello everyone,
Here is my data
create table experience (exp_id number(10), exp_name varchar2(20), root_exp_id number(10));
insert into experience values (642, 'Test', 5172);
create table experience_node (exp_node_id number(10), exp_node_type_id number(2));
insert into experience_node values (5172, 1);
insert into experience_node values (5173, 2);
insert into experience_node values (5174, 2);
create table experience_connector (exp_conn_id number(10), exp_conn_type_id number(2), exp_node_id number(10), parent_exp_node number(10) );
insert into experience_connector values (4287, 1, 5173, 5172);
insert into experience_connector values (4288, 2, 5174, 5173);
insert into experience_connector values (4289, 2, 5175, 5174);
When we run these queries:
select     parent_experience_node_id
from     experience_connector
where     experience_node_id = 5175;
select     parent_experience_node_id
from     experience_connector
where     experience_node_id = 5174;
select     parent_experience_node_id
from     experience_connector
where     experience_node_id = 5173;
select     parent_experience_node_id
from     experience_connector
where     experience_node_id = 5172;
gives 5174, 5173, and 5172 and null. exp_node_type_id = 1 and exp_node_conn_type_id = 1 indicate that it is at the root level. Hope my explanation is helpful. What I am trying to get is - to get great great grant parent for 5175 which is 5172. Is this possible to do this with SQL?
Thank you so much for you help.
Best,
Lakshmi

Answer 1

We can use "model clause" ;-)
create table T (id number(10), parentID number(10) );
insert into T values (5173, 5172);
insert into T values (5174, 5173);
insert into T values (5175, 5174);
commit;
select parentID
  from T
model RETURN UPDATED ROWS
dimension by(id)
measures(parentID)
rules(
parentID[9999] = parentID[5175],
parentID[9999] = parentID[parentID[9999]],
parentID[9999] = parentID[parentID[9999]]);
PARENTID
    5172
or
select parentID
  from T
model RETURN UPDATED ROWS
dimension by(id)
measures(parentID)
rules(
parentID[9999] = parentID[parentID[5175]],
parentID[9999] = parentID[parentID[9999]]);